It is known in the art to electrolytically treat liquids to allow separation of a broad range of contaminants including metals, solids, pathogens, colloids and other undesirable substances. Electrolytic treatment involves the use of an electrical field which is applied to a liquid contained in a chamber in order to coagulate and otherwise to allow for removal of impurities found in the liquid. One example of a prior art device and method for electrolytic treatment is disclosed in PCT Publication No. WO 9640591. According to this invention, a waste stream is first passed through a polarizing means having an electrical potential that is different than ground potential, and then passed through an electrocoagulation chamber including a plurality of elongate electrodes or electrocoagulation blades which have different electrical potentials in comparison to one another. A plurality of holes are provided in the electrodes to cause turbulence in the waste stream which, in turn, increases the efficiency of the electrocoagulation. Although this device may be adequate for its intended purpose, one disadvantage of this device is that the torturous flow path of the waste stream as it passes through the device requires the electrodes or electrocoagulation blades to be of a high strength to withstand the high water pressure which must be used in order to keep the waste stream from clogging. Because the blades of these devices have to be significant in size and strength, a limited number of them can be used in a specified volume which reduces the actual surface area available for electrocoagulation treatment. Additionally, these coagulation blades require higher input line voltages in order to obtain the desired amperage between the blades in the electrical field because their surface area is limited by the high pressure. Smaller plates can withstand higher pressures, but the ability to maintain a desired amperage is sacrificed because available blade surface area within an electrocoagulation device is directly related to the amperage which can be maintained. Additionally, the torturous path also causes problems due to trapped gases produced by the electrolytic reaction in the chamber which further increases the pressure upon the blades. Accordingly, a high powered pump must be used to overcome the natural tendency of the waste stream to clog within the chamber. This PCT publication encompasses the same subject matter as disclosed in U.S. Pat. No. 5,611,907 to Herbst, et al. and U.S. Pat. No. 5,423,962 to Herbst, and further includes subject matter not found in these other patents.
Other examples of electrolytic treatment devices are disclosed in U.S. Pat. No. 4,293,400 to Liggett and U.S. Pat. No. 4,872,959 to Herbst, et al. These devices utilize electrodes in the form of metal tubes or pipes but require great effort in repairing or replacing the tubes. This amount of down time is unacceptable for many commercial applications.
U.S. Pat. No. 5,043,050 to Herbst discloses flat electrodes used within a coagulation chamber; however, in order for the apparatus of this invention to be used, the edges of the coagulation chamber must be tightly sealed. After long periods of use, the seals are difficult to maintain.
U.S. Pat. No. 3,925,176 to Okert discloses the use of a plurality of electrode plates for electrolytic treatment of liquids. However, these plates are not intended to be removed either as a whole or individually. Furthermore, the device disclosed in this reference cannot be powered in a series electrical connection which is desirable in many circumstances.
U.S. Pat. No. 5,302,273 to Kemmerer discloses an ionic reaction device including a tubular housing with multiple circular electrode plates for the treatment of a fluid. Because of the torturous path utilized in the reaction chamber of this device, high pressures are required to move the liquid through the device, and the device appears susceptible to clogging and excessive gas buildup.
One shortcoming of all of the foregoing prior art references is that there is no means by which to transform the input line voltage to the voltage and amperage necessary to optimize the electrocoagulation treatment without having to use a separate transformer. In other words, the electrocoagulation chambers themselves do not have the capability to transform the input line voltage to a desired voltage and amperage within the electrical field of the electrocoagulation device.
Another shortcoming of the prior art which utilizes a torturous flow path is that the electrodes or electrocoagulation blades require precision holes to be cut to allow gaskets to be bolted between the blades in order to withstand the pressure created by the torturous path. Additionally, the blades have to be laser cut with extreme precision in order to maintain the exact desired path. Deviation from a predetermined path can result in clogging due to buildup of coagulated solids bridging between misaligned blades. These manufacturing requirements greatly add to the cost of building an electrocoagulation device.
Another shortcoming of the prior art, which includes many of those discussed above, is that the blades are not easily removable for replacement or cleaning. Particularly for those chambers utilizing a tortuous path, a great number of bolts and gaskets are required to keep them in alignment. Accordingly, these pieces of hardware must be removed in order to replace the blades.
Each of the foregoing disadvantages are overcome by the apparatus and method of this invention. Additionally, the apparatus and method of this invention achieve other advantages discussed more fully below.